This proposal describes efforts to analyze the mechanism for triggering bacterial spore germination in Bacillus megaterium QM B1551. Recent data indicate that a trigger reagent such as L-proline causes a stereospecific change in the biophysical property of the spore membranes as determined by fluorescence depolarization with 1, 6-diphenyl -1, 3, 5-hexatriene (DPH) as a probe. The change in DPH mobility will be examined in membranes from spores chemically modified to block triggering, spores with mutations for triggering and spores with modified lipids. Other techniques such as ESR, DSC and NMR will also be employed to correlate the physical properties of membranes with the in vivo properties of spores. Techniques are also described to alter the physical properties of spore membranes in vivo. Identification of the trigger site will be with a proline affinity analogue or by acetic anhydride modification of the membrane proteins and we will attempt to purify the proline site with the aim of determining what physical changes occur when L-proline interacts with its site in the spore.